28,179 research outputs found
An Adaptive Sampling Scheme to Efficiently Train Fully Convolutional Networks for Semantic Segmentation
Deep convolutional neural networks (CNNs) have shown excellent performance in
object recognition tasks and dense classification problems such as semantic
segmentation. However, training deep neural networks on large and sparse
datasets is still challenging and can require large amounts of computation and
memory. In this work, we address the task of performing semantic segmentation
on large data sets, such as three-dimensional medical images. We propose an
adaptive sampling scheme that uses a-posterior error maps, generated throughout
training, to focus sampling on difficult regions, resulting in improved
learning. Our contribution is threefold: 1) We give a detailed description of
the proposed sampling algorithm to speed up and improve learning performance on
large images. We propose a deep dual path CNN that captures information at fine
and coarse scales, resulting in a network with a large field of view and high
resolution outputs. We show that our method is able to attain new
state-of-the-art results on the VISCERAL Anatomy benchmark
On the Average Comoving Number Density of Halos
I compare the numerical multiplicity function given in Yahagi, Nagashima &
Yoshii (2004) with the theoretical multiplicity function obtained by means of
the excursion set model and an improved version of the barrier shape obtained
in Del Popolo & Gambera (1998), which implicitly takes account of total angular
momentum acquired by the proto-structure during evolution and of a non-zero
cosmological constant. I show that the multiplicity function obtained in the
present paper, is in better agreement with Yahagi, Nagashima & Yoshii (2004)
simulations than other previous models (Sheth & Tormen 1999; Sheth, Mo & Tormen
2001; Sheth & Tormen 2002; Jenkins et al. 2001) and that differently from some
previous multiplicity function models (Jenkins et al. 2001; Yahagi, Nagashima &
Yoshii 2004) it was obtained from a sound theoretical background
Adjuvants : an essential component of neisseria vaccines
Adjuvants may be classified into delivery systems and immune potentiator or modulator molecules based on their mechanism of action. Neisseria vaccines containing traditional adjuvants such as aluminium salts have existed for long time, but meningitis caused by Neisseria meningitidis serogroups, particularly serogroup B, continues to be a global health problem. Novel strategies have applied in silico and recombinant technologies to develop "universal" antigens (e.g. proteins, peptides and plasmid DNA) for vaccines, but these antigens have been shown to be poorly immunogenic even when alum adjuvanted, implying a need for better vaccine design. In this work we review the use of natural, detoxified, or synthetic molecules in combination with antigens to activate the innate immune system and to modulate the adaptive immune responses. In the main, antigenic and imune potentiator signals are delivered using nano-, micro-particles, alum, or emulsions. The importance of interaction between adjuvants and antigens to activate and target dendritic cells, the bridge between the innate and adaptive immune systems, will be discussed. In addition, nasal vaccine strategies based on the development of mucosal adjuvants and Neisseria derivatives to eliminate the pathogen at the site of infection provide promising adjuvants effective not only against respiratory pathogens, but also against pathogens responsible for enteric and sexually transmitted diseases
Curvature in causal BD-type inflationary cosmology
We study a closed model of the universe filled with viscous fluid and
quintessence matter components in a Brans-Dicke type cosmological model. The
dynamical equations imply that the universe may look like an accelerated flat
Friedmann-Robertson-Walker universe at low redshift. We consider here
dissipative processes which follow a causal thermodynamics. The theory is
applied to viscous fluid inflation, where accepted values for the total entropy
in the observable universe is obtained.Comment: 11 pages, revtex 4. For a festschrift honoring Alberto Garcia. To be
publishen in Gen. Rel. Gra
k-strings and baryon vertices in SU(N) gauge theories
It is pointed out that the sine law for the k-string tension emerges as the
critical threshold below which the spatial Z_N symmetry of the static baryon
potential is spontaneously broken. This result applies not only to SU(N) gauge
theories, but to any gauge system with stable k-strings admitting a baryon
vertex made with N sources in the fundamental representation. Some simple
examples are worked out.Comment: 4 pages, 4 figures, v2: reference added, v3: comments and references
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